Electronically pure single chirality semiconducting single-walled carbon nanotube for large scale electronic devices

ABSTRACT

An electronically pure carbon nanotube ink, includes a population of semiconducting carbon nanotubes suspended in a liquid, the ink being essentially free of metallic impurities and organic material, and characterized in that when incorporated as a carbon nanotube network in a metal/carbon nanotube network/metal double diode, a nonlinear current-bias curve is obtained on application of a potential from 0.01 V to 100 V. The ink can be used to prepare air-stable n-type thin film transistors having performances similar to current thin film transistors used in flat panel displays amorphous silicon devices and high performance p-type thin film transistors with high-κ dielectrics.

CROSS-REFERENCE(S) TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Patent ApplicationNo. 62/274,634, filed on Jan. 4, 2016, the content of which is herebyincorporated by reference herein in its entirety.

INCORPORATION BY REFERENCE

All patents, patent applications and publications cited herein arehereby incorporated by reference in their entirety in order to morefully describe the state of the art as known to those skilled therein asof the date of the invention described herein

TECHNICAL FIELD

This technology relates generally to high purity single-walled carbonnanotubes (SWCNTs). In particular, this invention relates to the use ofSWCNTs in electronic devices.

BACKGROUND

Single-walled carbon nanotubes (SWCNTs) have been attractingresearchers' attention for potential applications as field emissiontransistors for electronic devices, computers and thin film transistorbackplanes. The mixed nature of SWCNTs growth, however, has impededtheir implementation. One reason if the unavailability of high purity,single chirality SWCNTs. Current methods of purifying SWCNTs rely onoptical spectroscopic screening techniques that have proven unable toaccurately establish CNT purity. Devices using semiconducting SWCNTsdeemed ‘pure’ by optical screening methods ubiquitously show linearcurrent-to-bias (“I-V”) responses, violating semiconductorcharacteristics of metal/semiconductor Schottky contacts andillustrating the presence of metal impurities and metallic SWCNTs.

Semiconducting single-walled carbon nanotubes have demonstrated theability to be used in place of high performance silicon transistors forapplications in microprocessor and radio frequency devices.Semiconducting single-walled carbon nanotube (SWCNT) thin filmtransistors (TFTs) also exhibit promise for large size displaybackplanes. The majority of SWCNT TFTs were bottom gated with SiO₂ or A1₂O₃. The device performance on these bottom gated SWCNT FETs wereunstable and degraded after certain time, requiring polymerencapsulation or inorganic thin film passivation. In contrast, top-gatedSWCNT TFTs are stable and promising for real applications. A few topgated SWCNT TFTs have been reported using dielectric materials such asHfO₂, A1 ₂O₃, ZrO₂, and Y₂O₃ deposited using electron beam evaporationor atomic layer deposition. The dielectric materials of these successfuldevices were all deposited at low temperature (<150° C.).

Recently, the SiNx commonly used for amorphous silicon TFTs was adaptedto be used as dielectrics for SWCNTs TFTs. Silicon nitride gatedielectrics for top-gated carbon nanotube field effect transistorsshowing p-type characteristics were obtained using plasma enhancedchemical vapor deposition (PECVD) at 225° C. Both n-type and p-typecharacteristics of SWCNTs transistors with SiNx passivation films ortop-gated insulators have been observed based on different depositiontemperatures using catalytic chemical vapor deposition. At depositiontemperatures higher than 330° C., SWCNTs were destroyed. At a depositiontemperature around 270° C., the fabricated transistors were convertedfrom p-type to n-type characteristics. This was interpreted as due tothe removal of the adsorbed oxygen. At deposition temperatures between60° C. and 120° C., the carbon nanotube transistors retained theiroriginal p-type properties. Stable n-type SWCNTs TFTs have also beenobtained by annealing the devices with a Si₃N₄ layer deposited in aplasma-enhanced chemical vapor deposition system at 110° C. in nitrogenatmosphere at 200° C. for one hour, or by using PECVD directly depositedSi₃N₄ as dielectrics. More recently, SiO₂ bottom gated n-type SWCNTsTFTs having SiNx passivation deposited at 150° C. using PECVD werereported. No damage was induced using PECVD at 150° C., and the obtainedn-type characteristics were attributed to the doping of SWCNT by SiNx K(Si≡N⁺) centers, which sufficiently thinned the Schottky Barrier (SB) tothe conduction band to allow for efficient electron tunneling from thecontacts into nanotubes. The effects of metal/SWCNT contacts wereattributed to the wettability of metals to carbon nanotubes.

Schottky barriers occur when the semiconductors contact with the metals.Evidence of Schottky barriers was observed as inflection points inoutput characteristics of semiconducting carbon nanotube field effecttransistors. The linear conductances at low drain bias in the outputcharacteristics of SWCNT FETs with Schottky barriers have beenattributed to the tunneling effects, and the on-conductances (4e²/h) areused to determine Schottky barriers of SWCNT TFTs. Thus SWCNT TFTs havebeen considered Schottky Barrier transistors for the modulation of thecontact resistances, with the exclusive focus on transmission throughthe barrier by thinning the barrier and increasing the tunneling. Thesetheoretical explanations were based on back-gated SiO₂ dielectrics thatare purer and more defect free than silicon nitride dielectrics.

Although advances in SWCNT TFT performance has made some progress,devices with performances rivaling those of amorphous silicon baseddevices has been hampered by the quality of the available SWCNTs.

SUMMARY

In one aspect, electronically pure, semiconducting carbon nanotube(“e-CNT”) are provided. In particular, electronically pure,semiconducting single-walled carbon nanotube (“e-SWCNT”) inks areprovided.

In one aspect, an electronically pure carbon nanotube ink includes apopulation of single-walled semiconducting carbon nanotubes suspended ina liquid, the ink being essentially free of metallic impurities andcharacterized in that when incorporated as a carbon nanotube network ina metal/carbon nanotube network/metal double diode, a nonlinearcurrent-bias curve is obtained on application of a potential from 0.01 Vto 5 V.

In one or more embodiments, 99.9% or more or 99.99% or more of thecarbon nanotubes are semiconducting.

In one or more embodiments, the carbon nanotubes comprise one or morechiralities selected from (6,1), (5,3), (7,0), (6,2), (5,4), (8,0),(7,2), (8,1), (6,4), (7,3), (6,5), (9,1), (8,3), (10,0), (9,2), (7,5),(8,4), (11,0), (12, 2), (7,6), (9,4), (11,1), (10,3), (8,6), (9,5),(12,1), (11,3), (8,7), (13,0), (12,2), (10,5), (11,4), (9,7), (10,6),(13,2), (12,4), (14,1), (9,8), (13,3), (18,4), (20,2).

In one or more embodiments, the semiconducting carbon nanotubes are of asingle chirality, and can be (6,5) single-walled carbon nanotubes.

In one or more embodiments, the semiconducting carbon nanotubes are asingle tube diameter of 0.7 nm and length from 500 nm to 10 μm.

In one or more embodiments, the liquid comprises deionized water, andcan further include water soluble surfactants, such as for example,water soluble surfactants selected from the group of are sodium dodecylsulfate, sodium dodecylbenzene sulfate, sodium cholate, and sodiumdeoxycholate.

In another aspect, an electronically pure carbon nanotube thin filmincludes a population of single-walled semiconducting carbon nanotubesessentially free of metallic impurities and organic material, andcharacterized in that when incorporated as a carbon nanotube network ina metal/carbon nanotube network/metal double diode, a nonlinearcurrent-bias curve is obtained on application of a potential from 0.01 Vto 5 V.

In one or more embodiments, the semiconducting carbon nanotubes are asingle tube diameter of 0.7 nm and length from 500 nm to 5 μm.

In one or more embodiments, the carbon nanotube density is in a rangefrom 1-1000 nanotubes per μm².

In another aspect, the carbon nanotube film can be used to identify anelectronically pure carbon nanotube ink by providing a nanotube ink ofinterest; preparing a metal electrode/carbon nanotube network/metalelectrode double diode, using the carbon nanotube ink of interest;applying a voltage from 0.01 V to 5 V across the metal electrodes of thediode; and generating a current-bias curve, wherein a non-linear curveis an indication of an electronically pure semiconducting carbonnanotube ink.

In one or more embodiments, the nonlinear curve exhibits a power-lawbehavior.

In one or more embodiments, the electrodes are prepared from metalsselected from Au, Cr, Ag, Ti, Cu, Al, Mo, Pd, Pt, Sc, and/or theircombination.

In one or more embodiments, the electrodes define a channel length inthe range of 5 nm to ≥1 mm and a channel width in the range of 5 nm to≥1 mm.

In another aspect, a method of making an electronically pure carbonnanotube thin film includes treating a substrate by ozone, and coatingwith poly(l-Lysine); and applying an electronically pure semiconductingcarbon nanotube ink on the on poly(l-Lysine) treated substrate.

In another aspect, an n-type carbon nanotube thin film transistorsincludes an electronically pure semiconducting carbon nanotube thinfilm; drain/source metal electrodes in electrical contact with thecarbon nanotube thin film; an amorphous silicon nitride dielectricslayer; and a metal gate electrode, characterized in that the N-typecarbon nanotube thin film transistor shows amorphous silicon-liketransfer characteristics in which the current increases from <10⁻¹² A toat least 10⁻⁷ A when the gate voltage sweeps from 0 V to 20V under 0.1 Vdrain-source bias.

In one or more embodiments, the n-type carbon nanotube thin filmtransistor is characterized in that under V_(DS)=0.1 V, the I_(DS)increases from 1 fA at −5V to 0.1 μA at 30 V.

In one or more embodiments, the carbon nanotube density is in a rangefrom 1-1000 nanotubes per μm².

In one or more embodiments, the n-type carbon nanotube thin filmtransistor is characterized in that under V_(DS)=10 V, I_(DS)>30 μA at30 V.

In one or more embodiments, the thin film transistor demonstratesnegligible threshold shift after 10 V stress for one hour.

In one or more embodiments, the n-type carbon nanotube thin filmtransistor is characterized in that under V_(DS)=0.1 V, theI_(ON)/I_(OFF) ratio is >10⁸.

In one or more embodiments, the n-type carbon nanotube thin filmtransistor is characterized in that under V_(DS)=0.1 V, theI_(ON)/I_(OFF) ratio is in the range of 10⁶-10¹².

In one or more embodiments, the gate electrode is a top gate electrode.

In one or more embodiments, the gate electrode is a bottom gateelectrode.

In one or more embodiments, the thin film transistor is prepared usingan etch-stop process.

In one or more embodiments, the thin film transistor is prepared using aback channel etch process.

In one or more embodiments, the thin film transistor is air stable.

In one or more embodiments, the n-type carbon nanotube thin filmtransistors have channel lengths ranging from 5 nm to 1 mm or higher.

In one or more embodiments, the n-type carbon nanotube thin filmtransistors have channel widths ranging from 5 nm to 1 mm.

In one or more embodiments, the carbon nanotubes comprise one or morechiralities selected from (6,1), (5,3), (7,0), (6,2), (5,4), (8,0),(7,2), (8,1), (6,4), (7,3), (6,5), (9,1), (8,3), (10,0), (9,2), (7,5),(8,4), (11,0), (12, 2), (7,6), (9,4), (11,1), (10,3), (8,6), (9,5),(12,1), (11,3), (8,7), (13,0), (12,2), (10,5), (11,4), (9,7), (10,6),(13,2), (12,4), (14,1), (9,8), (13,3), (18,4), (20,2), such assemiconducting carbon nanotubes of a single chirality, and can be forexample, (6,5) single-walled carbon nanotube.

In one aspect, the semiconducting carbon nanotubes are a single tubedimension.

In another aspect, a p-type carbon nanotube thin film transistorsincludes electronically pure semiconducting carbon nanotube thin film;drain/source metal electrodes in electrical contact with the carbonnanotube thin film; a hafnium oxide dielectrics layer; a metal gateelectrode, characterized in that the p-type carbon nanotube thin filmtransistors show p-type transfer characteristics, in which underV_(DS)=1 V, the I_(DS) increases from <10⁻¹² A to at least 10⁻⁷ A whenthe gate voltage sweeps from 0 V to −20V under 1 V drain-source bias

In one or more embodiments, the p-type carbon nanotube thin filmtransistors is characterized in that the p-type carbon nanotube thinfilm transistors show p-type transfer characteristics, in which underV_(DS)=1 V, the I_(DS) increases less than 1 fA at 5V to 0.1 μA at −15V.

In one or more embodiments, the carbon nanotube density is in a rangefrom 1-1000 nanotubes per μm².

In one or more embodiments, the p-type carbon nanotube thin filmtransistors is characterized in that under V_(DS)=1 V, theI_(ON)/I_(OFF) ratio is >10⁸.

In one or more embodiments, the p-type carbon nanotube thin filmtransistors is characterized in that under V_(DS)=1 V, theI_(ON)/I_(OFF) ratio is in the range of 10⁶-10¹².

In one or more embodiments, wherein the thin film transistor is airstable.

In one or more embodiments, the p-type carbon nanotube thin filmtransistors have channel lengths ranging from 35 nm to 1 mm or higher.

In one or more embodiments, the p-type carbon nanotube thin filmtransistors have channel widths ranging from 5 nm to 1 mm.

The performances of top-gated (6,5) SWCNT thin film transistors (TFTs)are consistent and reproducible, remarkably different from thoseconstructed on optically pure semiconducting SWCNTs. The stable andinvariant device performances of (6,5) SWCNT can be ascribed to theiruniform diameter and chirality. TFT fabrication processes compatiblewith conventional amorphous silicon TFT fabrication and performancecharacteristics of SiN_(x) top-gated NMOS (6,5) SWCNT TFTs demonstratethe feasibility of producing high performance SWCNT TFT backplanes inexisting amorphous Si manufacturing lines. (6,5) SWCNT are compatiblewith high κ dielectrics used in ultrafast electronics, makingelectronically pure single chirality semiconducting (6,5) SWCNT inkpractical for applications in large scale electronics.

These and other aspects and embodiments of the disclosure areillustrated and described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the following figures,which are presented for the purpose of illustration only and are notintended to be limiting.

In the Drawings:

FIG. 1A is a vis-NIR absorption spectrum of an as prepared SWCNT ink(indicated by (6,5) arrows) with enriched (6,5) SWCNT according to oneor more embodiments of the invention and a SWCNT solution prepared usinga conventional high pressure carbon monoxide process, according to oneor more embodiments.

FIG. 1B is a photo image of 100 mL ink containing electronically pure(6,5) SWCNTs with concentration of 0.6 μm/mL, according to one or moreembodiments.

FIG. 1C is vis-NIR absorption spectrum (solid curve) and NIRfluorescence emission spectrum (dashed curve, excited at 532 nm) of theelectronically pure (6,5) SWCNT ink of FIG. 1B, according to one or moreembodiments.

FIG. 1D is a Raman Spectrum of the electronically pure (6,5) SWCNT inkof FIG. 1B, excited at 532 nm laser beam, according to one or moreembodiments; the enlarged RBM peak band at 310 cm⁻¹ is shown in theinsert box.

FIG. 2A is a photo image of Borofloat 33 glass (Diameter: 100 mm,Thickness: 500 μm) coated with (6,5) SWCNT thin films inside patternedAu/Cr electrodes with channel length of 5 μm and channel width of 100μm; and FIG. 2B is an enlarged image of FIG. 2A, according to one ormore embodiments.

FIG. 2C is an SEM image of (6,5) SWCNT thin film inside the patternedelectrodes showing tube length in the range of 1˜2 μm and tube densityof 4˜6 tubes per μm², according to one or more embodiments.

FIG. 2D is a plot of the measured current versus bias curve showingnonlinear behavior for a Schottky diode prepared using e-SWCNTs, whenprobed on two electrodes (inserted microimage) on a SemiProbe PS4L M12probe station with Keithley 4200 SCS, according to one or moreembodiments.

FIG. 2E shows a photograph of an altas DCA Pro controlled by laptop usedto characterize (6,5) SWCNT thin film on a small piece of silicon wafer(500 nm SiO₂) showing a nonlinear curve; gold electrodes were aerosoljet printed to form a device with channel length of 50 μm and channelwidth of 10 mm and bonded with two copper wires (diameter: 0.5 mm) forconnections with the altas DCA Pro.

FIG. 2F shows a photograph of a metal/SWCNT/metal double diode using(6,5) SWCNT coated quartz (2.5 cm×2.5 cm), on which two copper wires(0.5 mm) were bonded with silver paste to form a metal/(6,5) SWCNT/metaldevice with channel length of 2 mm, and channel width of 2.5 cm,according to one or more embodiments.

FIG. 3A is a photo image of 1440 unit (6,5) SWCNT TFTs fabricated usingphotolithography on Borofloat33 Glass (Diameter: 100 mm, Thickness: 500μm) of a fixed 5 μm channel length and a series of channel widths from 5μm, 25 μm, 50 μm, 75 μm to 100 μm, according to one or more embodiments.

FIG. 3B is a micro image of one SWCNT TFT with a channel width of 50 μm;and FIG. 3C is a schematic illustration of the SiN_(x) top-gated (6,5)SWCNT TFTs of FIG. 3B viewed from cross section, according to one ormore embodiments.

FIG. 3D is a plot showing the typical transfer characteristics of aSiN_(x) top-gated (6,5) SWCNT TFT with a channel width of 50 μm showingfA off-current and >10⁸ I_(ON)/I_(OFF) ratio by sweeping V_(Gate) from−5 V to 20 V (right I_(DS) is linear scale and left I_(DS) is log scale)under V_(DS)=0.1 V, according to one or more embodiments.

FIG. 3E is a plot showing the output characteristics of bending curvesby sweeping V_(DS) from 0V to 5V; the curves bend down as V_(Gate)switched from 20 V to 0 V with step of 2V, according to one or moreembodiments.

FIG. 3F is a plot showing the transfer characteristics of 20 SiN_(x)top-gated (6,5) SWCNT TFTs with channel width of 50 μm to illustrate thereproducibility and consistency of the devices, according to one or moreembodiments.

FIG. 3G is a plot showing the I_(ON)/I_(OFF) ratio variation ofdifferent channel widths eliciting consistent I_(ON)/I_(OFF) ratios in aseries of channel widths from 5 μm, 25 μm, 50 μm, 75 μm to 100 μm,reflective of an electronically pure semiconductor, according to one ormore embodiments.

FIG. 4A is a plot showing the typical transfer characteristics of a HfO₂top-gated (6,5) SWCNT TFT with a channel width of 50 μm showing fA-leveloff-current and >10⁸ I_(ON)/I_(OFF) ratio by sweeping V_(Gate) from 0 Vto −15 V (right I_(DS) is log scale and left I_(DS) is linear scale)under V_(DS)=−1 V.

FIG. 4B is a plot showing the output characteristics of a HfO₂ top-gated(6,5) SWCNT TFT with a channel width of 50 μm showing downward bendingcurves by sweeping V_(DS) from 0V to −8V; the curves moved down whenV_(Gate) switched from −14 V to −0 V with a step of 2V.

FIG. 5A is a schematic illustration of a CMOS inverter fabricated bywire bonding PMOS and NMOS (6,5) SWCNT TFTs; and FIG. 5B is a circuitdiagram of the CMOS (6,5) SWCNT inverter of FIG. 5A.

FIG. 5C is a plot showing the voltage transfer characteristics of a CMOS(6,5) SWCNT inverter showing a sharp inversion (solid curve) at V_(IN)=4V and corresponding voltage gain as large as 52 (dot curve).

FIG. 6 is a histogram of (6,5)SWCNT lengths extracted from SEM images,according to one or more embodiments.

FIG. 7 is a series of histograms showing the statistical analysis ofI_(ON)/I_(OFF) ratio for NMOS (6,5) SWCNT TFTs with different channelwidths, according to one or more embodiments.

FIG. 8 is a plot showing the transfer characteristics of NMOS (6,5)SWCNT TFTs with channel width of 50 μm, VDS=10 V, according to one ormore embodiments.

FIG. 9 is a plot showing the transfer characteristics of NMOS (6,5)SWCNT TFTs with channel width of 50 μm before and after 10 V bias stressfor 1 hour, according to one or more embodiments.

FIG. 10 is a plot showing the measured current versus bias curve showinglinear curve for a Schottky diode prepared using NanointegrisIsoNanotubes-S 99% semiconducting single-walled carbon nanotubes, whenprobed on two electrodes.

FIG. 11 is a plot of the typical transfer characteristics of SiNxtop-gated Nanointegris 99% semiconducting SWCNT (IsoNanotubes-S 99%semiconducting) TFT with channel width of 50 μm by sweeping V_(Gate)from −5 V to 20 V (right I_(DS) is linear scale and left I_(DS) is logscale) under V_(DS)=0.1 V.

FIG. 12 is a plot of the output characteristics of SiNx top-gated (6,5)SWCNT TFT using Nanointegris 99% semiconducting SWCNT (IsoNanotubes-S99% semiconducting) with channel width of 50 μm showing downward bendingcurves by sweeping VDS from 0V to 5V.

FIG. 13A-13D show a series of fabrication steps in the manufacture ofbottom-gated e-SWCNT TFTs, according to one or more embodiments.

FIG. 14 is cross-sectional view of an e-SWCNT TFT and a summary of theEtch-Stop process flow used in its manufacture, according to one or moreembodiments; demonstrating the compatibility of the e-SWCNT TFTfabrication process in conventional fabrication process flow designs.

FIG. 15 is cross-sectional view of an e-SWCNT TFT and a summary of theBack-Channel Etch (BCE) process flow used in its manufacture,demonstrating the compatibility of the e-SWCNT TFT in conventionalfabrication process flow designs.

DETAILED DESCRIPTION

Generally, carbon nanotubes can be either metallic or semiconductingalong the tubular axis. For a given (n,m) nanotube, if n=m, the nanotubeis metallic; if n−m is a multiple of 3, then the nanotube issemiconducting with a very small band gap, otherwise the nanotube is amoderate semiconductor. However, the presence of metallic CNTs in asemiconducting CNT ink degrades electronic performance. Moreover,currently there exists no reliable screening method to assess theelectronic purity of a CNT ink. Conventional spectroscopic methods suchas UV-vis spectroscopy, IR and Raman are not sufficiently sensitive todetect small amounts of metal impurities or the presence of metallicCNTs.

Electronically pure semiconducting carbon nanotubes (“e-CNTs”) and e-CNTinks are provided. The carbon nanotubes include single-walled carbonnanotubes.

In one or more embodiments, an electronically pure carbon nanotube inkincludes a population of single-walled semiconducting carbon nanotubessuspended in a liquid, the ink being essentially free of metallicimpurities and characterized in that, when incorporated as a carbonnanotube network in a metal/carbon nanotube network/metal double diode,a nonlinear current-bias curve is obtained on application of a potentialfrom 0.01 V to 5 V.

As used herein “electronically pure semiconducting carbon nanotubes”inks contain essentially only semiconducting single-walled carbonnanotubes and are essentially free of metallic impurities (typically dueto residual catalyst used in the synthesis of the CNTs), includingmetallic carbon nanotubes. “Free of metallic carbon nanotubes” refers toless than 0.01 wt % metallic CNT content. “Essentially free of metallicimpurities” refers to both metallic carbon nanotubes and metallicnanoparticles from the catalysts. The electronically pure semiconductingcarbon nanotubes are considered free of metallic impurities when the drySWCNTs contain less than 0.1 wt %, or even less than 0.05 wt % or lessthan or equal to 0.01 wt % metallic impurity. The amount of metallicimpurities can be in a range bounded by any value described hereinabove.The electronically pure semiconducting carbon nanotubes inks describedherein may be alternatively referred to as carbon nanotubes (CNTs) andsingle-walled carbon nanotubes (SWCNT); however, the e-CNT inks areconsidered to be single-walled to provide superior electrical andelectronic properties. Electronically pure carbon nanotube inks are alsocharacterized in that, when incorporated as a carbon nanotube network ina metal/carbon nanotube network/metal double diode, a nonlinearcurrent-bias curve is obtained on application of a potential sweep from0.01 V to 5 V.

In one or more embodiments, 99.9% or more of the carbon nanotubes aresemiconducting.

In one or more embodiments, 99.99% or more of the carbon nanotubes aresemiconducting.

In one or more embodiments, the semiconducting carbon nanotubes includeone or more of semiconducting carbon or single-walled carbon nanotubeshaving a chirality associated with semiconducting properties. Exemplarysemiconducting carbon nanotubes include semiconducting carbon nanotubeshaving a chirality of (6,1), (5,3), (7,0), (6,2), (5,4), (8,0), (7,2),(8,1), (6,4), (7,3), (6,5), (9,1), (8,3), (10,0), (9,2), (7,5), (8,4),(11,0), (12, 2), (7,6), (9,4), (11,1), (10,3), (8,6), (9,5), (12,1),(11,3), (8,7), (13,0), (12,2), (10,5), (11,4), (9,7), (10,6), (13,2),(12,4), (14,1), (9,8), (13,3), (18,4), (20,2) and combinations thereof.In one or embodiments, the electronically pure semiconducting carbonnanotubes are of a single chirality. In a particular embodiment, theelectronically pure semiconducting carbon nanotubes are (6,5)-SWCNTs.

In one or more embodiments, the e-CNTs and e-SWCNTs are provided in afluid as a suspension or dispersion, also referred to as an “ink.” Inone or more embodiments, the e-CNTs and/or e-SWCNTs are present in aconcentration in the range of 0.001 μg/mL to 1 mg/mL dispersed in asolvent such as de-ionized water. The dispersion can also include asurfactant, such as sodium dodecyl sulfate, sodium dodecyl benzenesulfate, sodium cholate, sodium deoxycholate and/or the like. Thesuspension is suitable for use as an ink for printing or depositinge-CNTs and e-SWCNTs as thin films and patterned films. For example, thee-CNTs and e-SWCNTs can be deposited as continuous thin films, andpatterning can be introduced post-deposition, such as by etching.Patterned films can also be obtained by direct printing.

e-CNT inks can optionally possess other characteristics and properties.For example, an e-CNT ink can have uniform CNT diameters and/or narrowdistribution of CNT lengths. In one or more embodiments, e-CNT inksinclude CNTs having lengths of between 0.5-2.0 microns. In one or moreembodiments, CNTs in the e-CNT ink are all or substantially all the samechirality with uniform diameter. CNT networks and thin films obtainedfrom deposition or printing of the e-CNT inks also have the above notedproperties.

In some embodiments, the e-SWCNT tube diameters can be in the range of0.5 nm to 3 nm. In some embodiments, the e-SWCNTs have a uniform tubediameter of about 0.7 nm as determined from SWCNT to SWCNT. SWCNTnetworks and thin films obtained from deposition or printing of thee-SWCNT inks also have the above noted properties.

In one or more embodiments, the e-SWCNTs are substantially a singlechirality. In one or more embodiments, the e-SWCNTs are substantiallyonly (6,5)SWCNTs. In one or more embodiments, greater than 90%, orgreater than 95% or greater than 96%, or greater than 97% or greaterthan 98%, or greater than 99% or up to 99.9 or up to 99.99% of theSWCNTs are of the same chirality. Chiral purity bounded by any of thevalues provided above is also contemplated. CNT networks and thin filmsobtained from deposition or printing of the e-CNT inks also have theabove noted properties.

The single chirality and uniform diameter of eSWCNTs can mitigate thevariation of carbon nanotube electric properties, and chemical and biointerfaces, rendering promising carbon nanotubes for practicalapplications in electronics and bio-sensing.

Single-walled carbon nanotube (SWCNT) networks deposited from, e.g., a(6,5) single chirality SWCNT aqueous solution (ink) can be characterizedas electronically pure semiconductors based on their performance in ametal/semiconductor Schottky contacts. In one or more embodiments,carbon nanotubes are electronically pure semiconducting carbon nanotubeswhen they show a non-linear current-bias (I-V) curve when a potentialsweep, e.g., a potential sweep of 0.01 V to 5 V, is applied to ametal/carbon nanotube network/metal double diode prepared from thecarbon nanotubes of interest. The current-bias curve can be obtainedusing either complex instruments or portable devices.

In one or more embodiments, a test is provided for determining whether aSWCNT ink is electronically pure. The test includes casting a test SWCNTsolution on a borosilicate glass substrate (such as Borofloat 33 glassavailable from Schottt, or substrate of comparable quality) that hasbeen treated with 0.1% poly(L-lysine) aqueous solution to form a uniformthin layer/film of SWCNTs, and evaporating a Cr(10 nm)/Au(40 nm) bimetallayer onto the SWCNT film to pattern electrodes with channel lengths andwidths of 5 μm and 100 μm, respectively. While the SWCNT density is notexpected to affect the nonlinearity of the Schottky diode, it may effectcurrent density, with higher SWCNT density providing higher currentdensity. The (6,5) SWCNT density in this particular embodiment is about5-6 nanotubes per μm², however, the actual SWCNT density can vary. Inone or more embodiments, the CNT density is in the range of 1-1000nanotubes per cm² and can be for example, 1-10 nanotubes per cm² or,10-50 nanotubes per cm² or, 50-100 nanotubes per cm² or 100-200nanotubes per cm² or 200-400 nanotubes per cm² or 400-600 nanotubes percm² or 600-800 nanotubes per cm² or 800-100 nanotubes per cm² or anyrange bounded by any value noted hereinabove. The metal/SWCNT/metaldouble diode is characterized with a semiconductor characterizationsystem such as Keithley 4200 SCS Parameter Analyzer (or any other devicecapable of applying a voltage sweep and monitoring current output) byapplying a potential sweep of 0.01V to 5.0 V across the two electrodesin air at room temperature. Nonlinearity at room temperature indicatesthat the test SWCNT thin film are electronically pure. In certainembodiments, the nonlinear curve exhibits a power-law behavior.

In certain embodiments, nonlinearity is established by comparison to a“goodness of fit” test for a linear curve. Measures of goodness of fittypically summarize the discrepancy between observed values and thevalues expected under the model in question. If the discrepancy iswithin an acceptable range, than the curve can be considered linear andthe material and device do not have the characteristics of theelectronically pure carbon nanotube ink described herein. For example, alinear regression model can be used to identify the relationship betweena current and voltage when all the other variables in the model are“held fixed”. If the correlation coefficient is greater than a statedvalue, for example greater than 0.90, or 0.91, or 0.92, or 0.93, or0.94, greater 0.95, or greater than 0.96, or 0.97, or 0.98 or 0,99, thanthe fit of the curve can be considered linear. A curve is considerednon-linear when the correlation coefficient in a linear regressionanalysis is less than 0.80, or less than 0.90.

Electronically pure semiconducting single-walled carbon nanotubes(e-SWCNTs) demonstrate many desirable properties, making them ideal foruse in a variety of electronic applications. In addition to use inSchottky diodes, e-SWCNTs can be incorporated into PMOS (p-typemetal-oxide-semiconductor) and NMOS (n-type metal-oxide-semiconductor)transistor devices and can be stacked to form CMOS (complementarymetal-oxide-semiconductor) inverters that demonstrate performancecharacteristics comparable to amorphous Si devices. Due to theelectronic purity of the e-CNTs incorporated into these devices,performances exceed those seen to date for traditional SWCNT TFTs.

Both large scale PMOS and NMOS devices can be fabricated using SWCNTthin films showing fA-level off current, e.g., 10⁻¹⁵-10⁻¹² A, andI_(ON)/I_(OFF) ratio in the range of 10⁶-10¹² and optionallyI_(ON)/I_(OFF) ratio >10⁸. CMOS inverters fabricated by wire bondingPMOS and NMOS SWCNT TFTs together can have large voltage gains, and thevoltage gain can be greater than 40, or greater than 45 or greater than50, and up to 200. In one embodiment, a CMOS inverter provided voltagegains as large as 52.

e-SWCNTs can be obtained using a starting material CNT solution that isenriched in carbon nanotubes having the desired chirality, e.g., (6,5)SWCNTs, and that has been prepared from a process that uses low catalystloads, e.g., less than 3 wt %, followed by careful purificationresulting in a SWCNT suspension. e-SWCNTs are purified usingultracentrifugation and/or precipitation of the SWCNT suspension toremove CNT bundles and metal nanoparticle catalysts, followed by two ormore separations by column chromatography.

Electronically pure carbon nanotubes can be extracted from a mixture ofas-grown carbon nanotubes, including carbon nanotubes obtained using atleast one of: arc-discharged growth, chemical vapor deposition,laser-ablation, and high pressure CO conversion, using density gradientultracentrifugation, gel chromatography, size-exclusion, HPLC, aqueoustwo phase partition, and/or organic materials wrapping.

Suitable raw materials for the production of e-CNTs include SWCNTsobtained using a high pressure carbon monoxide (HiPCO) process. TheHiPCO process was developed at Rice University to synthesize SWCNTs in agas-phase reaction of an iron catalyst such as iron carbonyl withhigh-pressure carbon monoxide gas. The iron catalyst is used to produceiron nanoparticles that provide a nucleation surface for thetransformation of carbon monoxide into carbon during the growth of thenanotubes. The process is run at elevated pressures, e.g., 10-300 atm(10-300 bar), and elevated temperatures, e.g., 900-1100° C., with CO andiron catalyst vapors being continuously fed into the reactor.

According to one or more embodiments, the HiPCO process is operatedusing feed conditions that favor the production of a single chiralitynanotube (e.g., a predetermined/selected chirality). In one or moreembodiments, the HiPCO process is modified to enrich the as-grown carbonnanotubes in the CNT of desired chirality. In one embodiment, the HiPCOprocess is modified to enrich the as-grown carbon nanotubes in (6,5)SWCNTs.

In particular, the HiPCO process can be performed using feed conditionsthat favor the production of (6,5) SWCNTs. In one exemplary process,conditions include 10 atm (10 bar) and 1100° C. In one or moreembodiments, the catalyst is selected to promote the production of aselected chirality, and in particular to promote the production of (6,5)chiral SWCNT. Exemplary catalysts include pentacarbonyliron,pentacarbonylcobalt, pentacarbonylnickel, pentacarbonymolybdenum, andpentacarbonylzirconium. Applicants have surprisingly found that theHiPCO process described herein can be run with low catalyst loads, e.g.,<3 wt. The use of low catalyst loads reduces the level of metalimpurities that need to be removed in subsequent purification processesand result in a lower metal content in the CNT ink.

FIG. 1A shows the spectra of as-made HiPCO CNT showing the differencefrom other HiPCO CNTs. FIG. 1A is a plot of vis (visible)-NIR (nearinfrared) absorption of a sample prepared according to a process inaccordance with some embodiments of the present disclosure, the plotshowing SWCNT solution enhanced in (6,5) SWCNTs (shown by arrow), ascompared to a conventionally HiPCO processed material. The curve 100shows increased absorbance in the 980-990 nm and 1100-1200 nm regions,which is indicative of an increase yield of (6,5) SWCNT as compared to aconventionally prepared SWCNT, such as that commercially available fromNanointegris shown as curve 110. The increased intensity of curve 100between 980-1220 nm demonstrate that the e-CNT ink according to one ormore embodiments of the invention is enriched in semiconducting SWCNTsby 2-fold as compared to the conventional CNT solution. Nanointegris 99%CNT inks contain many different species with different diameters andchiralities. In comparison, the electronically pure SWCNT inks onlycontain one diameter and one chirality.

The as-prepared SWCNTs are then purified to obtain the e-SWCNT ink.SWCNT raw powder enriched in (6,5) SWCNTs was prepared as describedabove using a Rice University Mark III high pressure carbon monoxidereactor (Batch number 190.1). The SWCNT raw powder was dispersed in 2%sodium dodecyl sulfate (SDS) aqueous solution (deionized water) using atip sonicator with 20 Watts of power for 8 hours. After ultracentrifugeor precipitation to remove carbon nanotube bundles and metalnanoparticle catalyst impurities, the decanted supernatant solution wastransferred to a Saphacryl S-200 gel column for carbon nanotubeseparation. The SWCNTs trapped in the gel were eluted out with 2% SDSsolution. After 4-6 cycles of gel chromatography, the pure purplesolution was collected in a concentration of 6 μg/mL. An image of thepurified solution is shown in FIG. 1B, and the purity of the solutionwas assessed initially using vis (visible)-NIR (near infrared)absorption, NIR fluorescence emission spectra and Raman spectroscopy.

FIG. 1C characterizes the final product with sole diameter of 0.7 nm andone chirality of (6,5). The Vis (visible)-NIR (near infrared) absorptionand NIR fluorescence emission spectra of the collected purple solutionwere recorded on an NS3 Applied Nano Spectralyzer at ambienttemperature, and are reported. In the absorption spectrum, two majorabsorbance peaks at 983 nm (extinction coefficient: 4400 M⁻¹cm⁻¹) and570 nm with FWHM (Full Width at Half Maximum) of 30.5 nm and 30 nm,respectively, are assigned to the S₁₁ and S₂₂ transition between the vanHove Singularities of (6,5) chirality SWCNT. A broad band between 800 nmand 880 nm is considered to be the sideband of the S₁₁ transition. Whenthe solution was excited with a 532 nm laser light source, thefluorescence emission was detected as a 986 nm peak with a FWHM of 26.5nm and a broad band between 1060 nm and 1160 nm, as illustrated by thedashed curve in FIG. 1C. The negligible Stokes shift (3 nm) and narrowFWHM indicate the high purity of (6,5) SWCNT. The solution was furthercharacterized with Raman spectroscopy on an NS3 Applied NanoSpectralyzer, and the corresponding Raman spectrum is shown in FIG. 1D.When the solution was excited with a 532 nm laser beam, the Ramanscattering was detected as a strong tangential G band (G from Graphite)at 1587 cm⁻¹ (ω_(G) ⁺, 15 cm⁻¹ FWHM) and 1525 cm⁻¹ (ω_(G) ⁻3 cm⁻¹ FWHM),a disorder induced D band in the range of 1200-1325 cm⁻¹, a second orderovertone G′ at 2617 cm⁻¹, and a weak RBM (Radial Breathing Model) bandat 310 cm⁻¹ (d_(t)=α/ω_(RBM)=248 cm⁻¹ nm/310 cm⁻¹=0.8 nm). These RamanScattering peaks correspond to sp² carbon-carbon stretching and radialexpansion-contraction of (6,5) SWCNT, further corroborating the resultsof Vis-NIR absorption and NIR fluorescence emission. The peak ratio ofD/G is estimated to be 0.03, reflective of less defective (6,5) SWCNT.The D/G ratio provide information about the quality of CNT and theamount of defect sites. The general D/G ratio is greater than 0.1, andthe electronically pure SWCNTs exhibit significantly less defects.

The utility of the e-SWCNTs described herein is further demonstrated bythe results of incorporation of the nanotubes into electrical andelectronic devices.

In one or more embodiments, e-SWCNTs are incorporated into a diode, suchas a Schottky contact, including metal electrodes evaporated on anelectronically pure semiconducting CNTs or SWCNTs thin film network, toprovide a diode demonstrating non-linear current-bias (I-V) curves. Inone example, the purple e-SWCNT solution was cast on 0.1% poly(L-lysine)aqueous solution treated Borofloat 33 glass (Diameter: 100 mm,Thickness: 500 μm) to form a uniform thin layer/film of (6,5) SWCNTswith high transparency. The resulting thin film is shown in FIG. 2A. Ontop of the (6,5) SWCNT thin film, Cr(10 nm)/Au(40 nm) bimetals wereevaporated to pattern electrodes with channel lengths and widths of 5 μmand 100 μm, respectively. The electrodes are shown in themicrophotograph in FIG. 2B. The (6,5) SWCNT thin film between twoelectrodes was imaged with an SEM (scanning electron microscope), andthe imaging revealed a layer of well-dispersed nanotubes in the form ofa network, as illustrated in FIG. 2C. The (6,5) SWCNT density is about5-6 nanotubes per μm². The average length of the (6,5) SWCNTs is about1-2 μm, as is illustrated in the histogram of FIG. 6 showing thedistribution of CNT lengths observed in by SEM. The metal/(6,5)SWCNT/metal double diodes were characterized with a Keithley 4200 SCS(Semiconductor Characterization System) (see the probes visible in theinset to FIG. 2D) in air at room temperature. A typical current-biascurve is displayed in FIG. 2D and has a pronounced gap-likenonlinearity. The curve seems to exhibit a power-law behavior, that iscurrent ∝ (bias)^(α), α>1. The nonlinearity at room temperatureindicates that (6,5) SWCNT thin film are semiconducting with essentiallyno metallic impurities. The devices are semiconducting SWCNT networksconnected to two metal contacts, that is, two Schottky-type diodesconnected back to back.

The nonlinear current-bias curve can be explored for the examination ofpurity of semiconducting SWCNTs electronically in an elegant andconvenient way. In this example, the purple e-SWCNT solution was cast ona small piece of a 0.1% poly(L-lysine) aqueous solution treated siliconwafer (1 cm×3 cm, 500 nm SiO₂) to deposit a (6,5) SWCNT thin film. Onthe top of the (6,5) SWCNT thin film, two 10 mm long gold electrodesseparated by 50 μm were aerosol jet printed using a suspension of 4 nmgold nanoparticles in xylene (40 weight %), followed by curing at 200°C. The two electrodes were contacted with two copper wires (diameter:0.5 mm) using silver paste and soldered with metal Tin (the insert toFIG. 2E). The simple metal/(6,5) SWCNT/metal chip was connected to anAtlas DCA Pro from Peak Instrument controlled with a laptop. As shown inFIG. 2E, the graph displays nonlinear curves. The purple solution wasalso cast on a 2.5 cm×2.5 cm quartz pretreated with 0.1% poly(L-lysine)aqueous solution to obtain a (6,5) SWCNT thin film. Silver paste wascast on the top of the (6,5) SWCNT thin film to form two 2.5 cm longsilver electrodes separated in 2 mm (FIG. 2F). A similar nonlinear curvewas observed. Thus, performance was substantially not affected by thechoice of metal electrodes. The generality of nonlinearity withdifferent metals in various substrates further demonstrated that these(6,5) SWCNT thin films deposited from purple solution are electronicallypure semiconductors.

The non-linearity of the current-bias curve displayed for diode devicesusing the e-SWCNTs of the current invention are compared to thetypically linear current-bias curve displayed for diode devices usingother semiconducting SWCNTs. FIG. 10 is a plot of the measured currentversus bias curve for a Schottky diode prepared using NanointegrisIsonanotubes-S 99% semiconducting single-walled carbon nanotubes. Whenprobed on two electrodes over a potential sweep of 0 V to 5 V, thecurrent-bias response is linear. Thus, despite representation by themanufacture of low metal content and 99% semiconducting SWCNT contents(see, e,g, Nanointegris Carbon Nanotube Material Data Sheet), devicesprepared using such SWCNTs do not demonstrate pure semiconductingbehavior.

In one or more embodiments, the e-SWCNTs can be incorporated into thinfilm transistors having channel widths ranging from 1 nm to 200 nm, or50 nm and higher. In one or more embodiments, top-gated NMOS and PMOSdevices incorporating electronically pure semiconducting CNTs or SWCNTscan be prepared. The NMOS and PMOS devices possess extremely low offcurrents, e.g., on the order of fA, and a high I_(ON)/I_(OFF) ratio,e.g., >10⁸ I_(ON)/I_(OFF) ratio. In certain embodiments, off currentscan be in the range of 10⁻¹⁵-10⁻¹² A and I_(ON)/I_(OFF) ratios can be inthe range of 10⁶-10¹².

In one or more embodiments, a top-gated SiN_(x) thin film transistor(TFT) is provided.

Generally, an electronically pure carbon nanotube thin film for use inpreparing thin film transistors can be prepared by applying the e-CNTink onto a suitably treated substrate. For example, substrates can betreated in an ozone oven, e.g., for 15 minutes, followed by treatmentwith a poly(l-Lysine) solution, e.g., with 0.1% poly(l-Lysine). Afterdrying, the electronically pure carbon nanotube ink can be directlycoated on poly(l-Lysine) treated substrates using conventional methodssuch as spraying, dipping, spin coating, and/or the like. Alternatively,the transparent electronically pure semiconducting single chirality(6,5) SWCNT thin film can be deposited with solution processes suitablefor roll-to-roll fabrication on transparent plastics like polyethylenefilm. The e-CNT thin film can be patterned using photolithography andetched by oxygen plasma. The (6,5) SWCNT thin film between twoelectrodes was imaged with an SEM, and was shown to exhibit a layercomprising a well-dispersed nanotube network. The (6,5) SWCNT densitywas about 5-6 nanotubes per μm², and the average length of the (6,5)SWCNTs was around 1˜2 μm.

In preparing an n-type thin film transistor, source/drain metalelectrodes can be deposited using conventional methods such as sputterdeposition, evaporation, or ebeam. The drain/source metal electrodes canbe patterned using photolithography and etched by dry-etch, wet-etch, orlift-off.

Silicon nitride has widely been used as the dielectric in amorphoussilicon thin film transistors. In preparing an n-type thin filmtransistor, an amorphous silicon nitride film (SiN_(x)) can be depositedwith plasma enhanced chemical vapor deposition (PECVD) at over a rangeof temperatures and feeding ratios, or sputtering. The energy levels ofdefect states in amorphous silicon nitride are used to identify thenature of trap states responsible for charge trapping. The interfaceprovides a channel for tailoring the free charge and trapped charge bygate potential. Both the interface and bulk properties of SiNxdielectrics depend on the deposition process and conditions involved:e.g., chemical vapor deposition, plasma deposition, sputteringdeposition at different temperatures, and NH₃/SiH₄ ratios. For example,the interface states between carbon nanotube and silicon nitridedielectrics can depend on the silicon nitride deposition method used,the feeding ratio and the temperature.

In one embodiment, electronically pure, single-chirality (6,5)single-walled carbon nanotube thin film transistors were fabricated withtop-gated SiNx deposited by sputtering at a substrate temperature of350° C. with a feeding ratio of 33.5 sccmNH₃/40 sccm SiH₄. In oneembodiment, SiNx is deposited using PECVD, at a temperature of 225° C.and a feeding ratio of NH₃/SiH₄ that was varied from 3 sccm/5.3 sccm, to10 sccm/5.3 sccm, to 15 sccm/5.3 sccm. Top-gated (6,5) SWCNT TFTs showedgood performance for SiNx deposited at low temperature (225° C.) with 10sccm NH₃/5.3 sccm SiH₄ feeding ratio. Without wishing to be bound bytheory, these obtained results were interpreted as the effect of theinterface states between (6,5) SWCNT and SiNx dielectrics that providethe channel for the applied gate potential to modulate the ratio of freeelectrons to trapped electrons by the defect sites in bulk SiNxdielectrics. In certain embodiments, an amorphous silicon nitride filmcan be deposited with plasma enhanced chemical vapor deposition at atemperature lower than 225° C., and a feed ratio of NH₃/SiH₄ greaterthan 1.

Gate metal electrodes can be deposited using conventional methodsincluding sputtering, evaporation, and ebeam deposition. Gate metalelectrodes can be patterned using photolithography and etched bydry-etch, wet-etch, or lift-off.

In one example, Borofloat33 Glass was coated with a thin layer/film of(6,5) SWCNTs, and about 1440 (row: 40, column: 35) unit thin filmtransistors (TFTs) of a fixed 5 μm channel length and a series ofchannel widths from 5 μm, 25 μm, 50 μm (3 rows), 75 μm to 100 μm (2rows) were fabricated using photolithography. The finishede-SWCNT/electrode system is shown in FIG. 3A. Next, Cr(10 nm)/Au(40 nm)bimetals were evaporated to pattern drain/source electrodes. The (6,5)SWCNT thin film was patterned by O² plasma etching. Over the patternedtransistors, a layer of 170 nm SiNx was deposited using plasma enhancedchemical vapor deposition (PECVD). Another Cr(10 nm)/Au(90 nm) layer wasevaporated to pattern gate electrodes on the SiNx layer. The SiNx layerover the drain/source test pads were opened using dry etching. Theformed (6,5) SWCNT TFT was photographed as shown in FIG. 3B. The crosssection diagram is presented in FIG. 3C. These (6,5) SWCNT TFTs werecharacterized with a Keithley 4200 SCS under a Semiprobe PS4L M12 probestation in air at room temperature. The typical transfer characteristicsof a (6,5) SWCNT TFT with channel width of 50 μm is presented in FIG.3D. Under V_(DS)=0.1 V, the I_(DS) increased from 1.8 fA to 0.22 μA whenV_(Gate) swept from −5 V to 20 V. It is worth noting that the fAoff-current of (6,5) SWCNT networks is similar to those of amorphoussilicon TFTs and comparable to those of single semiconducting SWCNTdevices. The device is an NMOS with I_(ON)/I_(OFF) greater than 10⁸. Itsthreshold voltage (V_(T)) is estimated to be 1.5 V and its subthresholdswing (ss) is estimated to be 592 mV/dec. The device was stressed withV_(DS)=10 V at room temperature for one hour, however, there wasnegligible V_(T) shift, as evidenced in the plot shown in FIG. 8. WhenV_(DS)=10V was applied, the on current reached 30 μA, which can be usedto drive organic light emitting diodes (see FIG. 9). Their outputcharacteristic is measured by sweeping V_(DS) from 0 V to 5 V, as isshown in FIG. 3E. The downward bending I_(DS)-V_(DS) curve moved downwhen V_(Gate) decreased from 20 V to 0 V with steps of 2V. The saturatedI_(DS) was observed when V_(Gate) was under 10 V. The electron mobility(μe) was estimated to be 0.5 cm²/Vs when capacitance per unit of SiNxwas 24 nF/cm². The transfer characteristics of over 20 devices with 50μm channel width were plotted in FIG. 3F showing repeatability andconsistency among devices. Their threshold voltage shifts are within±0.1 V. These performances resemble those of amorphous silicon TFTs.

The excellent uniformity demonstrates the reproducibility andconsistency of the (6,5) SWCNT TFTs described herein, as well as thegreat advantage of single chirality SWCNTs. About 98% of 1440 unitdevices were analyzed statistically, as shown in Table 1 and FIG. 7. Theremaining 2% of the 1440 unit devices were not considered due to theirdefects. Their I_(ON)/I_(OFF) ratio was plotted against W_(C)/L_(C), asshown in FIG. 3G, showing repeatability and consistency among devices.The overall I_(ON)/I_(OFF) is between 10⁶ and 10⁷ with less than 10%error bar. Significantly, the I_(ON)/I_(OFF) ratio does not vary withthe channel width (or the amount of (6,5) SWCNT), further illustratingthe electronically pure semiconducting nature of the (6,5) SWCNTs. Thevariation of I_(ON)/I_(OFF) ratio is within ±10%.

TABLE 1 Average threshold voltages of SiNx top-gated (6,5) SWCNT TFTswith different channel widths. Channel (width:length) 5:5 25:5 50:5 75:5100:5 Average V_(th) 0.95 0.70 0.76 0.61 0.59 # of valid data 109 127333 82 144

PMOS devices can be prepared using fabrication methods similar to thosedescribed above for NMOS devices. In preparing a p-type thin filmtransistor, hafnium oxide films can be used as the dielectric layer andcan be deposited with atomic layer deposition, evaporation (e.g.,electron beam evaporation), sputtering, and/or the like. In oneembodiment, hafnium oxide films can be deposited using atomic layerdeposition at temperatures lower than 225° C.

PMOS TFTs with (6,5) SWCNT thin films also were fabricated, by atomiclayer deposition of 30 nm HfO₂ dielectrics on Borofloat33 Glass with Pdas electrodes. The device dimensions are same as those of NMOS TFTs. Thetypical transfer characteristics of the (6,5) SWCNT PMOS TFT with achannel width of 50 μm is shown in FIG. 4A. The current (I_(DS)) of thePMOS device increased from <10 fA to 0.24 μA when the V_(Gate) was sweptfrom 1 V to −15 V. The fA off current and I_(ON)/I_(OFF)>10⁸ representedthe best performance of the p-type SWCNT TFTs, and were superior even tolow-temperature polycrystalline silicon TFTs. The output characteristicsof the (6,5) SWCNT PMOS TFT is exhibited in FIG. 4B with swept V_(DS)from 0 V to −8 V. The downward bending curves moved down when V_(Gate)went down from −14 V to 0V. The saturated on-current was observed underV_(Gate)<8V. It is worthy to note that there is a fundamental problemfor amorphous silicon, low-temperature polycrystalline silicone andmetal oxides to be modulated by high-κ dielectrics due to carrierscattering induced degradation of electrical properties. Devicesemploying the e-CNTs described herein can be used to producedsuperior-performing alternative devices for use with high-κ dielectricmaterials.

The low off-current and high I_(ON)/I_(OFF) ratio of SWCNT thin filmtransistor using the e-SWCNTs of the current invention are compared tothe transfer characteristics of thin film transistor devices using otherconventional semiconducting SWCNTs. FIG. 11 is a plot of the typicaltransfer characteristics of SiNx top-gated Nanointegris 99%semiconducting SWCNT (IsoNanotubes-S 99% semiconducting) TFT withchannel width of 50 μm by sweeping V_(Gate) from −5 V to 20 V (rightI_(DS) is linear scale and left I_(DS) is log scale) under V_(DS)=0.1 V.Similarly, output (B, D, F) characteristics of top-gated (6,5) SWCNTTFTs with SiNx dielectrics were determined. FIG. 12 shows the outputcharacteristics of SiNx top-gated (6,5) SWCNT TFT using Nanointegris 99%semiconducting SWCNT (IsoNanotubes-S 99% semiconducting) with channelwidth of 50 μm and showing downward bending curves by sweeping VDS from0V to 5V. The current e-SWCNTs have significantly better transfercharacteristics than top-gated (6,5) SWCNT TFTs with SiNx dielectricsusing the comparative ‘pure’ semiconductor carbon nanotubes, whichshowed only a 60 nA off-current, an I_(ON)/I_(OFF) ratio of about 100,and an electron mobility of 70.77 cm²/(V s).

In one or more embodiments, a test is provided for assessing whethersingle-walled carbon nanotube thin film transistors fabricated withtop-gated SiNx demonstrate properties of amorphous silicon TFTs. Atop-gated SiNx transistor is prepared by using a test SWCNT ink as thesemiconductor layer. By way of example, a single-walled carbon nanotubethin film transistor can be fabricated using the method set out in theexample section below. These devices are characterized using asemiconductor characterization system, such a Keithley 4200 SCS onSemiProbe PS4L M12 probe station (or other comparable system). Thetransfer characteristics of devices are obtained by sweeping the gatevoltage V_(G) at a rate of ˜0.5 V/s. The source-to-drain voltages arekept constant at settled voltage. The output characteristics of thedevices then are acquired by sweeping the source-to-drain voltage from 0to 5 V at a rate of ˜0.1 V/s. The gate voltage was kept constant from 20V to ˜4 V with interval of 2 V. The off currents and I_(ON)/I_(OFF)ratio are determined from the output. Test devices demonstrating low offcurrents, e.g., on the order of fA, and a high I_(ON)/I_(OFF) ratio,e.g., >10⁸ I_(ON)/I_(OFF) ratio, are deemed to be top-gatedsingle-walled carbon nanotube thin film transistors, according to one ormore embodiments of the invention. Off currents can be in the range of10⁻¹⁵-10⁻¹² A and I_(ON)/I_(OFF) ratios can be in the range of 10⁶-10¹².

With the performance characteristics of SiNx modulated (6,5) SWCNT TFTssimilar to amorphous silicon TFTs, the operation principal of amorphoussilicon TFTs can be readily applied to (6,5) SWCNT TFTs. Before thechannel was turned on, the large Schottky contact completely shut downthe channel same as metal/(6,5) SWCNT/metal at a low voltage bias. Afterthe channel was turned on but still under V_(T), the electron was drawnto form a depletion layer between (6,5) SWCNT and dielectrics inproportion to the increase in V_(G). But the current increasedexponentially (I_(DS)∝expr(vs/K_(b)it), q is the charge of an electron,kB is Boltzmann constant, T is temperature), as the band bendingincreased. After the depletion region was completed where V_(T) wasdefined (V_(S.)>V_(T)), metal/(6,5) SWCNT became an Osmic contact andthe current linearly increased with applied gate voltage(I_(DS)=k_(n′)W/L(VGS-V_(T)-V_(DS)/2)V_(D)S, k_(n′) is constant withunit A/V², W is channel width, L is channel length). This is due to thefurther drawn electrons occupying the conductive band to form aconductive channel by increasing V_(GS). This basic operation workssimilarly for HfO₂ modulated PMOS (6,5) SWCNT TFTs. Differently,negative V_(GS) forced holes to enter into the depletion region. Afterthe depletion region was completed (V_(GS)>V_(T)), the excess holesoccupied the valence band to form a conductive channel.

In one or more embodiments, a CMOS can be provided. The PMOS wafer wasmounted on NMOS wafer, wire bonding was used to connect the gateelectrode and one drain/source electrode of the PMOS (6,5) SWCNT TFT tothose of the NMOS (6,5) SWCNT TFT, as shown in FIG. 5A. The completedCMOS circuit was characterized using a 4200 SCS under a Semiprobe PS4LM12 probe station in air at room temperature. As shown in the inverterdiagram in FIG. 5B, a voltage supplier (V_(DD)=8V) was applied to thedrain electrode of PMOS (6,5) SWCNT TFT and the source electrode of NMOS(6,5) SWCNT TFT was connected to the ground. When input voltage (V_(IN))swept from 0 V to 8 V with an interval of 0.05 V, the measured outputvoltage remained high at 7.9 V before the sharp drop at 4V inputvoltage. After 4V input voltage, the output voltage remained a very lowvoltage at 0.1 V (FIG. 5C). By differentiating the V_(OUT)-V_(IN) curve,a voltage gain as large as 52 was obtained for (6,5) SWCNT CMOS inverter(dashed dot curve in FIG. 5C). This high voltage gain for carbonnanotube inverters is due to the high performance of the devices (fAoff-current and >10⁸ I_(ON)/I_(OFF) ratio). By changing the photomaskdesign used, PMOS and NMOS (6,5) SWCNT TFTs can be fabricated on acommon substrate, arranged in either a coplanar (2D) configuration, orvertically overlapping together (3D). The interconnections between PMOSand NMOS (6,5) SWCNT TFTs can be achieved with via drilling to formlogic circuits for macroelectronics applications with increasingfunction per area and less power dissipation.

The performance of both PMOS and NMOS (6,5) SWCNT TFTs can be furtherimproved with increasing on-current by shortening channel length orwidening channel width or increasing the density of SWCNT without thesacrifice of extremely low off current. From SEM images of currentdevices, the thickness of (6,5) SWCNT film is under 1 nm. The larger oncurrent is accomplishable for TFTs with thicker (6,5) SWCNT film >10 nm.For electronically pure semiconducting SWCNT, the off current will notvary with the amount of SWCNT such as channel width or thickness. Thus,both mobilities and I_(ON)/I_(OFF) ratios will be further improved withthick (6,5) SWCNT films. Statistically, the thick layer of (6,5) SWCNTfilm could eliminate device variation, especially with single chirality(6,5) SWCNT of uniform electrical properties. These confer (6,5) SWCNTsas the replacement of amorphous silicon (>100 nm), low temperaturepolycrystalline silicon (50 nm), and metal oxides (50 nm) for TFTbackplanes to meet the needs for emerging display commercial marketssuch as transparent, flexible and wearable displays. Further, with SWCNTalignment technologies and high-κ dielectrics, extremely high on-current(6,5) SWCNT TFT can be achieved with narrow channel length for highspeed and low power dissipation electronics. Electronically pure (6,5)SWCNTs can thus be practical for implementation into large-scaleelectronic applications.

Thin film e-SWCNT TFT devices in accordance with the present inventionmay have low operating voltages as low as about 5 V or less. TFTs mayhave low subthreshold slopes as low as about 600 mV/decade or less.e-SWCNT TFT devices TFT devices of the present invention provide anexcellent balance of high on-state currents, low operating voltage, andhigh on/off ratios. In one embodiment, the TFT device operates atvoltages of about 5 V or less with on/off ratios of about 10⁶ orgreater. e-SWCNT TFT solution are superior semiconductor materials forthe fabrication of semiconducting CNT network TFTs. Current densitiesare similar to those achieved at similar tube densities on amorphoussilicon, indicating that e-SWCNT inks and related films are excellentsemiconductor materials for TFTs fabricated by printing or othersolution-based processes.

Experimental Details

Materials:

Single-walled carbon nanotubes raw powder was produced in a RiceUniversity Mark III high pressure carbon monoxide reactor using lesscatalyst in a yield of 1 gram per hour.

In a 100 mL beaker, the mixture of 100 SWCNTs raw powder and 100 mL of2% sodium dodecyl sulfate (SDS, 99+% pure) aqueous solution weredispersed into 1 mg/mL solution using an ultrasonic processor (ColeParmer, 20 W) equipped with a 0.5-inch Ti flat tip for 20 hours undercontinuous water cooling. The residue catalyst, large nanotube bundlesand other impurities were removed via ultracentrifugation using aBeckman TL-100 ultracentrifuge equipped with a TLS-55 rotor. The top 90%of the supernatant was collected as the starting solution for gelchromatography.

Gel chromatography purification of SWNTs was performed using in-housepacked columns packed with allyl dextran-based gel beads following asimilar protocol in the literature.7 Briefly, a 20 mL of supernatantSWCNT solution was loaded to a column packed with 6 mL gel. Theunabsorbed SWNTs were washed off with 2% SDS solution and the adsorbedSWCNTs on the column were eluted using 5% SDS solution. The unabsorbedSWNTs were then load to the column and eluted in the same way for fourtimes. Then the (6,5) enriched fractions from the elution was thensubjected to fine purification by repeating gel chromatography 4-6 timesusing gradient SDS concentrations. Roughly about 50 mL of pure (6,5)SWCNT purple solution was collected in a concentration of 6 μg/mL within1 day.

The 2% SDS dispersed (6,5) SWCNT solution (15 mL, 6 μg/mL) was convertedinto 5% sodium cholate (SC) dispersed (6,5) SWCNT solution (6 mL, 15μg/mL).

Device Fabrication:

Substrates including Borofloat 33 glass (Diameter: 100 mm, Thickness:500 μm), Silicon wafer (SiO2 thickness: 500 nm) and quartz were treatedwith UV Ozone Cleaner (Jelight Model 42) for 15 minutes. Afterpoly(l-Lysine) aqueous solution (0.1 weight %) flew through thesubstrates, the substrates were extensively washed with de-ionizedwater. The substrates were blown dry and further have 5% SC dispersed(6,5) SWCNT solution (15 μg/mL) flow through. Then the substrate wascured on hotplate at 110° C. for 10 minutes and followed withextensively washing with de-ionized water. The substrates were blown dryand annealed in vacuum oven at 200° C. for 2 hours. Thus clean (6,5)SWCNT was uniformly coated in substrates. The size of substrates can beas large as 120 inch in diagonal for Gen10 manufacturing line.

Drain/Source electrodes were patterned with photolithography usingAZ2020 photo resistance gel. Then 10 nm Cr (0.5 A/s rate, 16% power) and40 nm (3 A/s rate, 22% power) were deposited in sequence using SloanE-Beam, and lift-off using acetone. For Pd electrodes, 40 nm Pd (3 A/srate, 22% power) was deposited using Sloan E-Beam, and lift-off usingacetone.

The (6,5) SWCNT thin film was patterned with photolithography using AZ5214 photo resistance gel. The unpatterned (6,5) SWCNT thin film wasetched with O₂ plasma (100 sccm flow, 100 W) using Oxford RIE and thenpatterned photo resistances were stripped off using acetone immediately.The 170 nm SiNx was deposited with plasma enhanced chemical vapordeposition (225° C., N2 100 sccm, He 400 sccm, NH₃ 10 sccm, SiH4 5.3sccm). The 30 nm HfO₂ was deposited with atomic layer deposition(CH₃-TEMAH-200-H₂O at 200° C., 0.1 nm/cycle rate).

Gate electrodes were patterned with photolithography using AZ2020 photoresistance gel. Then 10 nm Cr (0.5 A/s rate, 16% power) and 90 nm (3 A/srate, 22% power) were deposited in sequence using Sloan E-Beam, andlift-off using acetone. For Pd electrodes, 90 nm Pd (×3 A/s rate, 22%power) was deposited using Sloan E-Beam, and lift-off using acetone.

Drain/source pads were opened with photolithography using AZ 5214 photoresistance gel. The patterned SiNx or HfO₂ above drain/source pads weredry etched using Oxford RIE (3 sccm O2, 30 sccm CHF3).

Gold electrodes were aerosol jet printed using 4 nm gold nanoparticle inxylene (40 weight %) and cured at >200° C. for 30 minutes. Silver paste(SPI Chem ERL 4221 Epoxy Plasticizer) was used to bond copper wire (0.5mm in diameter) on substrates.

Measurements:

The Vis-NIR absorption, NIR fluorescence emission (excited at 532 nm)and Raman spectroscopy (excited at 532 nm) of (6,5) SWCNT purplesolution were measured on NS3 NanoSpectralyzer. SEM image of (6,5) SWCNTthin film was imaged with Stanford Nova NanoSEM. The current-biascurves, transfer characteristics, output characteristics and voltageoutput characteristic of Schottky diodes, NMOS and PMOS TFTs and CMOSinverters were measured with a Keithley 4200 SCS on SemiProbe PS4L M12probe station. The transfer characteristics of devices were obtained bysweeping the gate voltage VG at a rate of ˜0.5 V/s. The source-to-drainvoltage was kept constant at settled voltage. The output characteristicsof devices were acquired by sweeping the source-to-drain voltage from 0to 5 V at a rate of ˜0.1 V/s. The gate voltage was kept constant from 20V 210 to −4 V with interval of 2 V. The current-bias curves of copperwire (0.5 mm in diameter) bonded Schottky diodes were tested with anAtlas DCA Pro analyzer/curve tracer from PEAK Instruments.

Preparation of E-CNT Thin Film Transistors Using ConventionSemiconductor Fabrication Processes

The fabrication steps used in the manufacture of a bottom-gated e-SWCNTTFTs is described. The process demonstrates that e-SWCNT TFTs canreadily be integrated into conventional TFT fabrication processes.

The fabrication of an e-SWCNT TFT is shown in FIGS. 13A-13D. FIG. 13Ashows the deposition and definition of the metal gate (M1. FIG. 13Bshows the sequential deposition of the SiN gate dielectric, asemiconducting layer of e-SWCNTs, and an SiN etch-stop layer. The SiNetch stop layer is etch backed to form an SiN etch stop pad (M2). Theprocess is similar to that for conventional a-Si:H TFT, except that aSWCNT thin film layer is used instead. The SWCNT layer can be put downusing spin coating or other liquid deposition method that is readilyintegratable into the conventional semiconductor fabrication line. Next,as shown in FIG. 13C, the n+ conductive layer is deposited and the TFTisland is defined (M3). In FIG. 13D, a metal layer is deposited anddefined to form the source and drain metal contacts, the n+ conductivematerial is removed to expose the SiN etch stop (M4), and a finalpassivation layer is deposited and a contact window opening is formed tothe source, drain and gate metal contacts (M5).

In the Etch-Stop process, the contact window is formed by etching backto the SiN etch stop pad. FIG. 14 shows a cross-sectional view of ane-SWCNT TFT and processing modules of the Etch-Stop process used inmaking the final device architecture.

An alternative process includes formation of e-SWCNT TFT using BackChannel Etch (BCE) processing. As shown in FIG. 15, the contact windowis formed by etching back to the underlying SWCNT layer. FIG. 15 shows across-sectional view of an e-SWCNT TFT and the Back Channel Etch (BCE)processing modules used in making the final device architecture. Theprocess flow can be readily integrated into existing semiconductorfabrication processes.

The e-CNT inks and e-CNT thin films can be used in conventional devices,with minimal modification of existing fabrication methods. Theperformances of both top-gated and bottom-gated single chirality SWCNTthin film transistors (TFTs) are consistent and reproducible, remarkablydifferent from those constructed on optically pure semiconductingSWCNTs. The stable and invariant device performances of e-SWCNT can beplausibly ascribed to their uniform diameter and chirality. TFTresembled fabrication processes compatible with conventional amorphoussilicon TFT fabrication and performance characteristics of SiN_(x)top-gated and bottom gated e-SWCNT TFTs demonstrate the feasibility ofproducing high performance SWCNT TFT backplanes in existing amorphous Simanufacturing lines. E-SWCNT are compatible with high κ dielectrics usedin ultrafast electronics, making electronically pure single chiralitysemiconducting SWCNT ink practical for applications in large scaleelectronics.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimswhich follow.

Unless otherwise defined, used or characterized herein, terms that areused herein (including technical and scientific terms) are to beinterpreted as having a meaning that is consistent with their acceptedmeaning in the context of the relevant art and are not to be interpretedin an idealized or overly formal sense unless expressly so definedherein. For example, if a particular composition is referenced, thecomposition may be substantially, though not perfectly pure, aspractical and imperfect realities may apply; e.g., the potentialpresence of at least trace impurities (e.g., at less than 1 or 2%) canbe understood as being within the scope of the description; likewise, ifa particular shape is referenced, the shape is intended to includeimperfect variations from ideal shapes, e.g., due to manufacturingtolerances. Percentages or concentrations expressed herein can representeither by weight or by volume.

Although the terms, first, second, third, etc., may be used herein todescribe various elements, these elements are not to be limited by theseterms. These terms are simply used to distinguish one element fromanother. Thus, a first element, discussed below, could be termed asecond element without departing from the teachings of the exemplaryembodiments. Spatially relative terms, such as “above,” “below,” “left,”“right,” “in front,” “behind,” and the like, may be used herein for easeof description to describe the relationship of one element to anotherelement, as illustrated in the figures. It will be understood that thespatially relative terms, as well as the illustrated configurations, areintended to encompass different orientations of the apparatus in use oroperation in addition to the orientations described herein and depictedin the figures. For example, if the apparatus in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the exemplary term, “above,” may encompass both an orientation ofabove and below. The apparatus may be otherwise oriented (e.g., rotated90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Further still, in thisdisclosure, when an element is referred to as being “on,” “connectedto,” “coupled to,” “in contact with,” etc., another element, it may bedirectly on, connected to, coupled to, or in contact with the otherelement or intervening elements may be present unless otherwisespecified.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of exemplary embodiments.As used herein, singular forms, such as “a” and “an,” are intended toinclude the plural forms as well, unless the context indicatesotherwise.

It will be appreciated that while a particular sequence of steps hasbeen shown and described for purposes of explanation, the sequence maybe varied in certain respects, or the steps may be combined, while stillobtaining the desired configuration. Additionally, modifications to thedisclosed embodiment and the invention as claimed are possible andwithin the scope of this disclosed invention.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods, and systems for carryingout the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

What is claimed is:
 1. An electronically pure carbon nanotube ink,comprising: a population of single-walled semiconducting carbonnanotubes suspended in a liquid, the ink being essentially free ofmetallic impurities and wherein the ink is characterized as beingelectronically pure when incorporated as a carbon nanotube network in ametal/carbon nanotube network/metal double diode, by obtaining anonlinear current-bias curve through the application of a potential from0.01 V to 5 V across the semiconducting carbon nanotube network diode.2. The electronically pure carbon nanotube ink of claim 1, wherein 99.9%or more of the carbon nanotubes are semiconducting.
 3. Theelectronically pure carbon nanotube ink of claim 1, wherein 99.99% ormore of the carbon nanotubes are semiconducting.
 4. The electronicallypure carbon nanotube ink of claim 1, wherein the carbon nanotubescomprise one or more chiralities selected from (6,1), (5,3), (7,0),(6,2), (5,4), (8,0), (7,2), (8,1), (6,4), (7,3), (6,5), (9,1), (8,3),(10,0), (9,2), (7,5), (8,4), (11,0), (12, 2), (7,6), (9,4), (11,1),(10,3), (8,6), (9,5), (12,1), (11,3), (8,7), (13,0), (12,2), (10,5),(11,4), (9,7), (10,6), (13,2), (12,4), (14,1), (9,8), (13,3), (18,4),(20,2).
 5. The electronically pure carbon nanotube ink of claim 1,wherein the semiconducting carbon nanotubes are of a single chirality.6. The electronically pure carbon nanotube ink of claim 4, wherein thecarbon nanotubes are (6,5) single-walled carbon nanotube.
 7. Theelectronically pure carbon nanotube ink of claim 1, wherein thesemiconducting carbon nanotubes are a single tube diameter of 0.7 nm andlength from 500 nm to 10 μm.
 8. The electronically pure carbon nanotubeink of claim 1, wherein the liquid comprises deionized water.
 9. Theelectronically pure carbon nanotube ink of claim 1, wherein the inkcomprises water soluble surfactants.
 10. The electronically pure carbonnanotube ink of claim 9, wherein the water soluble surfactants areselected from the group of are sodium dodecyl sulfate, sodiumdodecylbenzene sulfate, sodium cholate, and sodium deoxycholate.
 11. Anelectronically pure carbon nanotube thin film, comprising: a populationof single-walled semiconducting carbon nanotubes essentially free ofmetallic impurities and organic material, and wherein the film ischaracterized as being electronically pure when incorporated as a carbonnanotube network in a metal/carbon nanotube network/metal double diode,by obtaining a nonlinear current-bias curve through the application of apotential from 0.01 V to 5 V across the semiconducting carbon nanotubenetwork diode.
 12. The electronically pure carbon nanotube thin film ofclaim 11, wherein 99.9% or more of the carbon nanotubes aresemiconducting.
 13. The electronically pure carbon nanotube thin film ofclaim 11, wherein 99.99% or more of the carbon nanotubes aresemiconducting.
 14. The electronically pure carbon nanotube thin film ofclaim 11, wherein the carbon nanotubes comprise one or more chiralitiesselected from (6,1), (5,3), (7,0), (6,2), (5,4), (8,0), (7,2), (8,1),(6,4), (7,3), (6,5), (9,1), (8,3), (10,0), (9,2), (7,5), (8,4), (11,0),(12, 2), (7,6), (9,4), (11,1), (10,3), (8,6), (9,5), (12,1), (11,3),(8,7), (13,0), (12,2), (10,5), (11,4), (9,7), (10,6), (13,2), (12,4),(14,1), (9,8), (13,3), (18,4), (20,2).
 15. The electronically purecarbon nanotube thin film of claim 14, wherein the semiconducting carbonnanotubes are a single chirality.
 16. The electronically pure carbonnanotube thin film of claim 14, wherein the carbon nanotubes are (6,5)single-walled carbon nanotube.
 17. The electronically pure carbonnanotube thin film of claim 11, wherein the semiconducting carbonnanotubes are a single tube diameter of 0.7 nm and length from 500 nm to5 μm.
 18. The electronically pure carbon nanotube thin film of claim 11,wherein the carbon nanotube density is in a range from 1-1000 nanotubesper μm².
 19. A method of identifying an electronically pure carbonnanotube ink, comprising: providing a nanotube ink of interest;preparing a metal electrode/carbon nanotube network/metal electrodedouble diode, using the carbon nanotube ink of interest; applying avoltage from 0.01 V to 5 V across the carbon nanotube network diode; andgenerating a current-bias curve, wherein a non-linear curve generated bythe carbon nanotube network diode is an indication of an electronicallypure semiconducting carbon nanotube ink.
 20. The method of claim 19,wherein the nonlinear curve exhibits a power-law behavior.
 21. Themethod of claim 19, wherein a curve is considered non-linear when thecorrelation coefficient in a linear regression analysis is less than0.90.
 22. The method of claim 19, wherein a curve is considerednon-linear when the correlation coefficient in a linear regressionanalysis is less than 0.80.
 23. The method of claim 19, wherein theelectrodes are prepared from metals selected from Au, Cr, Ag, Ti, Cu,Al, Mo, Pd, Pt, Sc, and/or their combination.
 24. The method of claim19, wherein the electrodes define a channel length in the range of 5 nmto >1 mm and a channel width in the range of 5 nm to >1 mm.
 25. A methodof making an electronically pure carbon nanotube thin film comprising:treating a substrate by ozone, and coating with poly(I-Lysine); andapplying the electronically pure semiconducting carbon nanotube ink ofclaim 1 on the poly(I-Lysine) treated substrate.